Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
  • H01M4/134—Electrodes based on metals, Si or alloys
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
  • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/04—Processes of manufacture in general
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/04—Processes of manufacture in general
  • H01M4/0438—Processes of manufacture in general by electrochemical processing
  • H01M4/0459—Electrochemical doping, intercalation, occlusion or alloying
  • H01M4/0461—Electrochemical alloying
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/04—Processes of manufacture in general
  • H01M4/0483—Processes of manufacture in general by methods including the handling of a melt
  • H01M4/0488—Alloying
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
  • H01M4/139—Processes of manufacture
  • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/36—Selection of substances as active materials, active masses, active liquids
  • H01M4/362—Composites
  • H01M4/366—Composites as layered products
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/36—Selection of substances as active materials, active masses, active liquids
  • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
  • H01M4/386—Silicon or alloys based on silicon
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/64—Carriers or collectors
  • H01M4/66—Selection of materials
  • H01M4/663—Selection of materials containing carbon or carbonaceous materials as conductive part, e.g. graphite, carbon fibres
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M2004/021—Physical characteristics, e.g. porosity, surface area
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
  • H01M2004/027—Negative electrodes
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries

Definitions

• the present invention relates to advanced, ex-situ (before cell assembly), pre-lithiated negative electrode (body) based on group IV semiconductors according to claim 1 .
• the inventive silicon anode as an alkali-ion battery and preferably to a lithium-ion secondary battery exhibits self-standing and/or heterofibrous and/or wafer-like and/or monolithic structures with high degree of structural ordering.
• This invention offers the possibility to engineer thick silicon electrodes featuring tailored weak and rigid points in its structures to buffer the volumetric expansion during charge/discharge cycles in a predicted manner, overcoming the uncontrolled volumetric expansion in the state of art silicon anodes. Definitions of the invention are given after the “object of the present invention” for each aspect of the inventive anode.
• a spun silicon-based mat made from a mixture of a liquid silicon precursor and polymer, wherein lithium is introduced in the silicon matrix of the resulting nanotubes of the spun mat.
• SoH state of health
• Li-ion battery with high cycle life and high charge rate acceptance is in direct conflict at least with the present types of alkali-ion anodes which are mostly based on Li+ intercalation reaction into graphite.
• the slow Li+ diffusion on intercalation into graphite together with the presence of concentration polarization gradient further restrict accessibility of Li+ by hampering the transport rate of Li+ from electrolyte to anode. This phenomenon then exceeds Li diffusion-intercalation rate and induce accumulation of more charge carriers on the anode surface and drives the anode potential below 0 V.
• Silicon as is one of the most promising type of anode for the post-lithium batteries which are based on alloying redox reactions with theoretical room temperature gravimetric/volumetric capacity in de-lithiated (discharged) state 3579 mAh/g, 8334 mAh/cm3 and lithiated Li3.75Si (charged) state 1857 mAh/g, 2193 mAh/cm3, while average discharge potential of 0.4 V vs. Li/Li+.
• Lithium metal anode volumetric capacity in fully discharged state is 0 mAh/cm3 so all lithium was stripped down from e.g., a Cu foil during discharge and transferred towards the cathode. So, lithium in fully charged state has a capacity of 2061 mAh/cm3 compared to silicon which has in fully discharged state a capacity of 8334 mAh/cm3 and fully lithiated - charged state 2193 mAh/cm3. So those numbers disclose advantages of using lithiated silicon anode instead of LMA (lithium metal anode). This is because theoretical volumetric fluctuation of lithium metal is 100% represented by average 0.205 mAh/cm2 per 1 micron of thickness. Thus, a LMA anode is dimensionally unstable.
• LMA volumetric fluctuation
• the inventive ex-situ pre-lithiated heterofibrous silicon anode with preferably an artificial SEI layer, having mixed ion-electron conductivity is a new and viable solution for the next generation batteries, capable to accept high charge rates and realize ultra-compact batteries with capacities over 1200 Wh/I and 350 Wh/kg with Li-rich LLS cathode.
• Si is a group IV type semiconductor with conductivity of 1.6x10-3 S/m and Li+ diffusivity of 1.9x10-14 cm2/s, but the Li+ diffusion in Si proceeds by different speeds according to the Si crystal orientation and thus the direction is 3D. While the critical force (1 ) in ⁇ 100> and ⁇ 111 > orientation is about 40% and 15% lower than in ⁇ 110>), which means that lithium atoms have a preferred diffusion rate in ⁇ 110> direction.
• a negative electrode - heterofibrous, lithiated silicon anode preferably exhibiting hierarchical electrode porosity, for an alkali-ion battery exhibiting an significantly improved cycle life, high coulombic efficiency, gravimetric and volumetric energy density, active mass utilization level and innovative production methods characterized as preferably solvent-free and/or binder-free and/or drying-free and/or slurry-mixing & degassing-free and/or slurry coating-free and/or anode current collector foils to tab welding-free and/or calender-free anode (and process of preparation) which together brings a high energy, cost efficiency and environmentally positive effect of such advanced silicon anode.
• heterofibrous, preferably aniso- tropically, lithiated, (preferably n-type) silicon wafer anode defined here at cell level as full charge of cell from 15% SoC to 100% SoC in preferably ⁇ 12min would have global impact on the alkali-ion battery market.
• (Monolithic) Wafer may mean: self-standing and/or heterofibrous and/or silicon (or in general group IV semiconductor)-based anode and/or unified anode body made from heterofibrous silicon material having preferably tailored hierarchical open porosity.
• Self-standing may be understood as a structural property.
• Such anode is capable of keeping its structure without external support such as an external backbone that only serves structural rigidity purposes and would take away space in the anode which could otherwise be used for the active material. Just as it is expected from a wafer.
• heterofibrous fibers refers to a possible variation in length and/or diameter of the same.
• Monolithic may refer to the shape and/or structure of the active anode material made from layers of fibers by fusing them together in the inventive way which results in a unified active anode material body.
• the inventive negative electrode may be used in an alkali-ion rechargeable battery and comprises an electrochemically active material of the anode wherein the active material is selected from the Group IV semiconductors and/or the active material is provided as a heterofibrous and/or wafer-like and/or self-standing and/or monolithic anode body and/or the anode body comprises at least 2 (individual/discrete) layers of aligned and/or stacked and/or interlaced fibers and/or the at least two layers are arranged parallel on top of each other and/or the layers are interconnected at multiple discrete interconnection sites, preferably interconnection points, via metallurgical bonds and/or the metallurgical bonds comprise or consist of Li-Group-IV- semiconductor-alloy and/or lithium or a mixture of the two and/or the discrete interconnection sites are distributed across the anode body, preferably discretely distributed over the, more preferably whole, area of the layers and/or the metallurgical bonds extend in an out-of-plane direction with
• the inventive electrode may also be described as a negative Li + host type alloying electrode.
• the present invention may also refer to an anode comprising at least 2 (individual/discrete) layers of aligned and/or stacked and/or interlaced fibers wherein the at least 2 layers are arranged parallel on top of each other wherein the layers are interconnected at multiple discrete interconnection sites, preferably interconnection points, via metallurgical bonds, wherein the metallurgical bonds comprise or consist of Li-Group-IV- semiconductor-alloy and/or lithium or a mixture of the two wherein the metallurgical bonds extend in and out of the plane direction with respect to the individual layers and are spacers between the layers, the gaps between the layers formed by the spaces can be filled with the silicon-lithium alloy formed during charging/lithiation of the anode, wherein the anode comprises an SEI-layer the volume/extension of which is adapted to the volume of the anode in the maximum lithiated state.
• Such SEI-layer may be formed by over lithiation of the anode and subsequent formation of an artificial SEI- layer via dopants or electrolytes which consumes the excess of lithium (preferably from about Li2iSi5 to about LhsSU) while the silicon lithium alloy has its maximum volume. Thereby, the SEI-layer does not experience forced expansion during charging of an according battery with such anode.
• Unevenly distributed lithiation or anisotropic lithiation of the layers comprise non-lithi- ated, deficiently lithiated and stoichiometrically lithiated areas.
• Spot-fusing which may also be called interconnection sites as a synonym, means metallurgical bonds from Li-Group-IV-semiconductor-alloy and/or lithium or a mixture of the two, the layers are interconnected at multiple discrete points by the metallurgical bonds and the discrete points of interconnection are spread across the anode body, hence over the whole area of the layers.
• discrete may mean separated from each other or individually introduced or having space between them or a combination the same.
• Interconnection sites are located between the layers and may extend into the layers for improved anchoring.
• Spot-fusing at certain positions may additionally guide the subsequent distribution of LixSi(y) in the anode during cycling controlling the way how LixSi(y) will redistribute in the anode.
• the mechanical stress coming from cycles of lithiation and de-lithiation charging/discharging can therefore be distributed.
• “Anisotropy” is a way how the deposition of Li in the anode as LixSi(y) can be predicted and guided during further repeating charging/discharging cycles. It ' s like chassis of modern car in which structure engineers insert weak spots which will guide during an accident how the chassis will deform and absorb the energy from the crash. The spot fusing may do the same inserting weak spot into structurally rigid LixSi anode body.
• the metallurgical bonds are preferably introduced by electrochemically induced Li fusing or introduction of molten lithium. Locations, distribution, shape, size and numbers of those fused spots can be extracted from the analysis of current distribution nonuniformity within LixSi(y) anode. Techniques for the current analysis include galvanos- tatic, potentiostatic and impedance spectroscopic measurement techniques. Furthermore, the distribution of the fused spots can be derived via in-situ and/or ex-situ imaging techniques like scanning electron microscope and transmission electron microscopy, whereby elemental mapping via energy-dispersive X-ray spectroscopy elucidates the location of metallurgic bonds and the presence of density gradients.
• Tortuosity of the anode is directly linked to the accessibility of the straightest and shortest possible electron and ion conduction paths established for Li+ by electrolyte present within the internal voids of electrode and for e- direct physical interaction of active mass with conductive additives such as carbon black or conductive polymers and/or its combination with.
• T raditional slurry-based electrode lack of structural ordering which is crucial for obtaining efficient electron and ion paths while monolithic silicon anode with high degree of structural ordering defined as hierarchical structure. This consist from layers of aligned silicon fibers stacked into the monolithic anode structure and is therefore able to establish efficient paths.
• Monolithic silicon anode with ordered porosity replaces traditional mediated electron conduction paths characteristic for slurry- based electrodes which are based on direct physical contact between silicon, conductive agents, binder and current collector foil by the inventive direct lithium-fused fibrous low resistive heterofibrous silicon anode body.
• This type of open structure allows fast charging of the anode beyond the critical limit of the existing intercalation type anode present at 80 % SoC.
• the artificial SEI layer may be made by the following steps. Interconnected layers of Si-fibers are lithiated (over lithiated) to L iS . Such lithiation may be conducted under elevated temperature preferably above 100°C under a protective solvent such as e.g., linear, branched or cyclic alkanes (Adv. Energy Mater. 2019, 1902116; DOI: 10.1002/aenm.201902116). Suitable solvents may be binary and or ternary mixtures of polar and non-polar solvent or solvents where more preferably non-polar solvent is hydrocarbon such as decane and polar solvent with boiling point > 130°C such as DEGDME diethylene glycol dimethyl ether.
• a protective solvent such as e.g., linear, branched or cyclic alkanes (Adv. Energy Mater. 2019, 1902116; DOI: 10.1002/aenm.201902116).
• Suitable solvents may be binary and or ternary mixtures of polar and non-polar solvent or solvent
• the (over) lithiated Si-layers are then treated with dopants to form an artificial SEI layer, preferably in a maximum lithiated stated of the Si-anode.
• the reaction of the dopants with the lithiated anode reduces the lithium content.
• a stoichiometry of LiisSU may be reached by/after artificial SEI formation which is stable at room temperature.
• the aSEI layer Since the SEI layer is induced artificially after the lithiation of the Si-Anode the aSEI layer has less imperfections (cracks, weak spots, thickenings,%) since there is only SEI formation at the end of the initial lithiation process and hence no volume expansion happens after SEI formations occurs (as it is the case if SEI is formed before or during initial lithiation process).
• the protective solvent prevents formation of the thick SEI layer at an earlier stage of/during lithiation.
• SEI formation may be conducted in the protective solvent into which liquid/dissolved and/or gaseous dopant (e.g. As-, P-, (H)F-compounds) such as group V pnictogens or low concentration electrolyte are introduced alternatively or additionally the SEI-layer may be introduced by reaction of the over-lithiated LbiSb with an electrolyte such as used in a final battery.
• liquid/dissolved and/or gaseous dopant e.g. As-, P-, (H)F-compounds
• group V pnictogens or low concentration electrolyte e.g. As-, P-, (H)F-compounds
• electrolytes may be chosen from e.g., ceramic solid electrolytes, polymer electrolytes, ionic liquids as known to the person skilled in the art.
• lithium reacts with the dopant and/or electrolyte forming a tailored (artificial) SEI layer containing e.g., LbP, LbAs, LUAs and/or LiF depending on the used dopant and/or electrolyte.
• a tailored (artificial) SEI layer containing e.g., LbP, LbAs, LUAs and/or LiF depending on the used dopant and/or electrolyte.
• room temperature active alloy such as LiisSU
• the resulting artificial SEI layer experiences mixed ion-electron conductive properties.
• the amount of Dopant in the Si-Layer can be adapted to the amount of Li present in the Lh-iSis to yield the desired Lithiation degree.
• This method reduces the loss of Li during the initial formation of the SEI layer compared e.g., to the classical lithiation of the final battery by initial charging. Furthermore, since the SEI is formed when the LixSi(y) species, such as LteiSis, has his higher volume, no crack of the SEI can occur by the volume expansion of the silicon, which is more often the case during silicon anode operations
• Common Li-ion cells contain a certain amount of lithium inserted/intercalated into NMC cathode which means that battery is in fully discharged state where all lithium is at the cathode side.
• the anode In order to move Li + from the cathode into the anode, the anode needs initial charging, however during this process, a high irreversible loss of Li takes place.
• This Li is consumed by the SEI buildup as a non-active part of the SEI layer and because of the high reactivity of lithium, thick highly resistive RSEI) is formed. In additional, this affects the Ret high charge transfer resistance (kinetics of electrochemical reaction).
• This common in-situ process uses only Li which is present in the cell as part of the energy storage matrix.
• the lithiation is done in-situ such as by mixing of suitable Li precursor capable to be part of the slurry or to be sprayed over the surface of electrode to be lithiated and subsequently activated by calendaring, cracking the protective layer of SLMP as “2010 DOE Vehicle Technologies Program Review” P.l. Marina Yakovleva Co-P.l. Dr. Yuan Gao FMC June 8th, 2010 (https://www.energv.gov/sites/prod/files/2014/03/f11/es011 vakoyleva 2010 o.pdf).
• the in-situ lithiated electrode will lead to a super expensive method, since building a protective layer over the micronized lithium metal powder introduced ex-situ during cell assembly but has to be activated subsequently.
• the preferred ex-situ introduced lithium which was supplied externally can be a. provided in excess, therefore allowing to achieve 100% of the theoretical cell capacity and b. provide a uniform SEI layer with little to none cracks, weak spots, thickenings, etc. since formation of the SEI layer is conducted in a maximum expanded state (by volume) i.e. (over) lithiated state of the anode - LteiSis. This method may also avoid inclusions of SEI layer material inside the LixSi(y) body.
• existing silicon-based anodes are based on intrinsic silicon where nanoparticles have various shapes such as 0D, 1 D or more complex 3D host structures for silicon or micro-meso porous 3D silicon or etched silicon anode body.
• 0D silicon particles having under critical diameters which prevents particles to rupture during lithiation (expansion) is having protective carbon coating on its surfaces where such coating is more preferably carbon.
• This type of protective coating represent barrier for lithium initiated self-fusing of surrounding silicon structures in close physical contact.
• traditional silicon anodes protective coating based on partial oxidation of the surface of silicon and or carbon coating those processes are applied to deal with pyrophoric nature of nano-sized silicon particles and ability to be processed as slurry with suitable solvent without significant side reaction.
• barrier layers between silicon particles in slurry-based electrode doesn’t allow lithium to efficiently propagate self-fusing process over the full electrode.
• Slurry based silicon electrodes keep their internal electron conduction paths dominated by physical contacts between active mass particles - silicon and surrounding particles, conductive additives such as 1 D shape as CNT and or 0D as carbon black and polymeric binders where our invention of heterofibrous anisotropically pre-lithiated monolithic silicon anode use preferably advantageous lithium initiated self-fusing process of silicon to build innovative fully interconnected monolithic 3D (wafer-like) anode.
• an object of the invention is an engineered hetero-fibrous and/or monolithic silicon anode body with functional anisotropy represented by the introduction of specific areas (fig. 7) into the monolithic silicon body which further comprises combinations of structurally rigid (fused parts of the lithiated layers) and weak spots (non-lithiated and or partially lithiated and or fully lithiated and/or over-lithiated parts of the layers). They together may form an engineered electrode superstructure capable to re-distribute volumetric fluctuation of silicon by allowing weak areas to absorb and redistribute it.
• Those areas may preferably be oriented in plane of electrode to accommodate volumetric changes and re-distribute it, preferably according pre-defined direction where rigid spots are preferably oriented out of plane and interconnect silicon layers.
• the diameter of the fused spot or line is preferably in the range of 1 to 1500 pm, more preferably in the range of 375 pm.
• the outer-side distance of the fused spots or lines is preferably in the range of 50 to 3000 pm, more preferably in the range of 750 pm, whereby the fusing spots and/or lines may feature a certain geometric pattern (spiral, star-shaped, hexagonal, etc.) and/or an uneven distribution.
• the fused spots may be provided as part of the structural integrity of the (wafer-like) stack of layers of Si-fibers.
• the number of fusing spots may be chosen accordingly to provide for at least an initial support of the overall anode structure.
• Anisotropic lithiation may be provided by the above stated discrete lithiation process, since Lithia- tion is oriented within and/or between the provided layers and is therefore provided with a defined plane and direction of extension.
• the spots may also add high degree of structural strength and partial flexibility to deal with silicon anisotropy on cycling. Additionally, to the (anisotropic) fusing spots fig.
• an anisotropically aligned Si-Li alloy-pattern is provided on and within the (wafer-)structure/layer structure/Si-fi- bers with preferably lithiated parts distributed over the total anode body (wafer)/layer structure and non-lithiated or Li deficient parts in the first process step distributed over the total anode body (wafer)/layer structure at the same time (see fig. 2 for example).
• Such alignment may also be called functional anisotropy by lithiation and forming Li-Si alloy with structural aka. flexural modulus gradient between spot-fused pillars.
• Lithiation may generally be established by a print-fuse method with liquid lithium and/or its alloys and/or electrochemical lithiation and/or its combination where more preferential it’s a two-step lithiation.
• Spot-fused may mean: o the layers are interconnected at multiple discrete points by metallurgical bonds and/or o connected in individual single places and/or areas and/or lines o at the discrete points of interconnection Li-Group-IV-semiconductor- alloy and/or lithium or a mixture of the two is provided as the metallurgical bond material, and/or o the discrete points of interconnection are distributed across the anode body, hence over the whole area of the layers and/or o the layers are spaced apart from each other, preferably by the material of the discrete points of interconnection and/or o the metallurgical bonds extend in an out-of-plane direction with respect to the individual layers, the meaning of spot-fused goes beyond a mere connection in single dots and may also include lines and/or areas and/or pillars. Those may have the properties as outlined in thus patent application.
• distribution or degree of lithiation within the layers varies, wherein the degree of lithiation of the anode body cross to the plane of extension of the layers is similar
• the present invention is directed to a negative electrode for the use in an alkali-ion rechargeable battery, wherein the electrochemically active material of the anode is selected from the Group IV semiconductors.
• the active material may be provided as a heterofibrous and/or wafer-like and/or self-standing and/or monolithic anode body.
• the anode body comprises at least 2 layers of aligned and/or stacked and/or interlaced fibers which are spot-fused together by the presence of lithium at multiple discrete points of their physical contact forming individual Li-Group-IV- semiconductor-alloy (e.g., LiSi-alloy) bonds between the layers.
• the anode body in particular the layers, are anisotropically lithi- ated.
• the spot fusing may at least in one aspect of the present invention represent at least a part of the anisotropic lithiation.
• the anode as mentioned above may contain an excess of lithium, at least in a charged state, within the anode body which may not necessarily be involved in the bonding of the layers. This additional lithium may be present as e.g., charge carrier, preferably within the individual layers.
• an object of the invention is a production of well aligned and/or interlaced and/or stacked self-standing layers comprising (preferably consisting of) silicon nano or microfibers and or silicon nano or micro rods, thus crystalline and/or amorphous and/or poly-crystalline silicon, preferably from suitable hydrogenated silicon precursors which are preferably liquids within the operating window of nano and or micro fibrous production apparatus, preferably defined between m.p. -55°C to b.p. 420°C.
• Silicon precursors include, but are not limited to cyclic silanes (SinFten, where n > 3) e.g. cyclohexasilane Si6Hi2, (m.p. +16.5, b.p.
• the Si precursor may also carry dopant and or dopants which is/are crosslinked with the Si precursor e.g. forming a copolymerized Si/dopant solution prior to a fiber spinning process or growing Si rods, wires having nano and or micro dimensions.
• Si and Si-fibers are also meant to apply to any group IV semiconductor or a mixture of them.
• a suitable liquid silicon precursor could also be poly(silanes) such as dimethyl-pol- ysilane (DMPS), deca-phenyl-penta-silane (DPPS) and poly-methyl-phenyl silane (PMPS) and/or suitable n-type dopant could be phosphorus bromine PBr3.
• DMPS dimethyl-pol- ysilane
• DPPS deca-phenyl-penta-silane
• PMPS poly-methyl-phenyl silane
• suitable n-type dopant could be phosphorus bromine PBr3.
• a first possible method for the production of the silicon layer is electrospun of a (polymeric) solution onto a substrate, and subsequent thermal decomposition by means of a heating treatment and/or laser treatment and/or microwave treatment, in order to obtain a silicon layer made from rods and/or wires having nano and or micro dimensions, which can be doped or not.
• the same operation is carried out by electrospinning a second layer of (polymeric) silicon precursor and subsequently thermally decomposition to obtain a second silicon layer.
• the operation can be repeated X times to obtain X stacked/interlaced silicon layers.
• a second possible method is based on carbonaceous seed carriers decorated with suitable catalyst (e.g., gold, silver nickel, etc.) capable to form intermetallic compound with silicon on the growing process.
• suitable catalyst e.g., gold, silver nickel, etc.
• Those seed carriers are in the shape of 0D ((sili- con)-nanocrystals, quantum dots) 1 D (CNT) and/or 2D (graphene, mxenes, silicon nanosheets) and/or 3D (reduced graphene oxide foam, MOF) carbon-based materials.
• Those seed materials decorated with the mentioned nucleation seeds may be aligned by dielectrophoresis at the top of a solution containing the co-polymerized Si/dopant mixture, which can be dissolved in hydrocarbon or mix of hydrocarbons, such as paraffin for example.
• a system of current collectors can be implemented in different geometry, for example such as a hexagonal one, containing 3 cathodes and 3 anodes. The alignment of these seed carriers will create an electronic percolation network which will short circuit the cathode/anode pairs.
• This short circuit will create heat by the Joule effect at the surface of the seed carriers, which triggers the thermal decomposition of the silicon precursor and a silicon layer made of rods and/or fibers, and/or wires having nano and or micro dimensions will be obtained.
• this silicon layers can be doped by various n-types (e.g., phosphorus) or p-type (e.g. boron) via addition of suitable dopant precursors (e.g. B2H6, pnictogenes, etc.) in the precursor solution.
• n-types e.g., phosphorus
• p-type e.g. boron
• suitable dopant precursors e.g. B2H6, pnictogenes, etc.
• Several layers can be obtained by stacking up the dielectrophoresis electrodes in a hexagonal system by an electric insulator, in order to obtain a stack of electrodes.
• the good production of the described anodes can be monitored by scanning electron microscopy to confirm the morphology of the silicon monolith, as well as micro tomography to ensure the good distribution and position of the fusing point.
• usual galvanostatic cycling method can be implement as well as cyclic voltammetry, where the anodic and cathodic peaks should be included in less than 0.2 V, translating the good kinetics of the electrochemical reactions, and thus an appropriate morphology of the silicon anode for ionic and electronic diffusion, as well as efficient charge transfer phenomena.
• the ex-situ lithiated anode represents the fully charged state of an electrochemical half-cell based on the fabricated silicon anode with a suitable lithium free cathode e.g., sulfur
• the electrochemical cell features an open circuit potential greater than 0 V, as for the example sulfur a potential of 2.1 V is observed.
• the full lithiation of the ex-situ fabricated LhsSU anode e.g., of 100 mg
• the initial discharge reaches the complete theoretical capacity (185 mAh in the case of a 100 mg LhsSU anode).
• the beneficial build-up of the ex-situ fabricated SEI is shown via repeated charging/discharging of the such fabricated anode without losing capacity due to the formation of lithium consuming in-situ SEI build up.
• the structural integrity of the ex-situ SEI in combination with the anisotropic lithiation results in a capacity retention of up to 90% of the initial discharge capacity over up to 1 ,000 charge/discharge cycles at current densities 3 C.
• Another object is a spot-fusing of the resulting monolithic heterofibrous silicon anode e.g., initiated by the alloying reaction between lithium and/or binary lithium alloy and or ternary lithium alloy and or lithium salt.
• a suitable solvent for alloying Li with Si and capable to solubilize lithium salt where more preferably lithium salt is LiTFSI and suitable solvents are e.g. binary and or ternary mixture of polar and non-polar alkane solvent where more preferably non-polar solvent is hydrocarbon such as decane and polar solvent is diethylene glycol dimethyl ether where boiling point of solvents is higher than 130°C and where molarity of LiTFSI within the electrolyte is ⁇ 0.75 M where more preferably 0.25 M.
• pre-lithiation is introducing structural lithium (e.g. Dots/ lines - Fig. 1 , 2, 3) before setting up a battery so pre-lithiated silicon anode is a structure which contain lithium and/or Li-Si alloy.
• structural lithium e.g. Dots/ lines - Fig. 1 , 2, 3
• this invention includes environmentally positive electrode which is fabricated from a slurry free process and/or is not based on an anode material slurry and/or binder free and/or drying free and/or calender free manufacturing methods
• a negative electrode - heterofibrous silicon anode where selected active material is heterofibrous ex-situ pre-lithiated and/or where the content of silicon in anode is > 72% per wt. more preferably a 92% where more preferably the state of silicon anode pre-lithiation depends on the content of available lithium in cathode where together forming a well-balanced Li-ion cell.
• a negative electrode - heterofibrous silicon anode is provided where the size of fibers/rods/wires/tubes is between 120nm - 15pm and where thickness of the heterofibrous silicon (wafer-like) anode is between 10 pm to 800 pm.
• a method of preparation of a negative electrode - heterofibrous silicon anode where silicon fibers are prepared from silicon precursor preferably with suitable dopant and/or dopants, preferably form a homogeneous mixture which is preferably partially co-polymerized prior to entering a fiber forming process.
• the present invention may also be directed to a negative electrode for the use in an alkali-ion rechargeable battery, wherein an electrochemically active material of the anode is selected from the Group IV semiconductors characterized in that the active material is provided as a heterofibrous and/or wafer-like and/or self-standing and/or monolithic anode body, wherein the anode body comprises at least 2 layers of aligned and/or stacked and/or interlaced fibers which are spot-fused together at multiple discrete points by individual Li-Group-IV-semiconductor-alloy and/or lithium bonds between the layers and that the anode body, in particular the layers, are anisotropically lithiated.
• an electrochemically active material of the anode is selected from the Group IV semiconductors characterized in that the active material is provided as a heterofibrous and/or wafer-like and/or self-standing and/or monolithic anode body, wherein the anode body comprises at least 2 layers of aligned
• a novel safety improving concept fig. 9 of using beneficial anisotropic properties of 2D graphene foil aka paper is provided such as higher thermal and electronic conductivity in-plane direction than through plane so such net-shaped graphene current collector foil fig. 8 with integrated current collector tab and or tabs which mimics the shape of electrode fig. 7 due the anisotropy allow to efficiently remove and redistribute electron as well as remove heat from or to cell.
• Fig. 10-13 depict model-like the influence of Lithium on the active mass material of the anode during construction of the anode.
• Fig. 14 and 15 depict the influence of lithiation an de-lithiation on the structure of the anode layers (structural expansion and shrinking of the layers) between the fusing- spots in particular according to claim 1 .
• the monolithic and/or wafer-like and/or self-standing architecture further comprises at least 2, preferably at least 3 hetero-fibrous silicon layers stacked and/or interlaced Fig. 4, 5 between each layer wherein preferably such silicon structure is subsequently convertible into a monolithic body by lithiation Fig. 6.
• the present invention may also be directed to a negative electrode for the use in an alkali-ion rechargeable battery, comprising an electrochemically active material of the anode and/or the active material is selected from the Group IV semiconductors and/or the active material is provided as a heterofibrous and/or wafer-like and/or self-standing and/or monolithic anode body and/or the anode body comprises at least 2 layers of aligned and/or stacked and/or interlaced fibers and/or the layers are spot-fused (Fig. 1 and/or 2 and/or 3).
• the anode body has an artificial ex-situ SEI layer over the entire surface of anode body (wafer).
• a method of producing a negative electrode - heterofibrous silicon anode where anisotropic (over)-lithiation of silicon fiber layers is provided by a molten lithium print-fusing method preferably within the temperature range of 45°C - 750°C via a melt printer and/or lithium dispenser, wherein the melt-printer head preferably follows a pre-defined trajectory to place fuse spots and preferably create functional anisotropy (anisotropic lithiation) at the anode defined as patterns or spots.
• a method of producing a negative electrode - heterofibrous silicon anode where anisotropic (over)-lithiation of the silicon fiber layers is provided e.g., by an electrochemical method preferably within the temperature range of suitable lithium electrolyte 100°C to 250°C in which the whole silicon anode body (wafer) is immersed.
• Glass, ceramic and or glass-ceramic sheet of solid-state electrolyte may divide operating pre-lithiation chamber into two independent cathode/anode compartment which allow to use various types of suitable Li+ sources such as molten lithium metal and or thick lithium metal foil and or liquid lithium rich donor electrolyte such as U2S6 in organic solvents and or U2SO4 in polar protic solvent such as water and Cu 2+ sacrificial electrode.
• suitable Li+ sources such as molten lithium metal and or thick lithium metal foil and or liquid lithium rich donor electrolyte such as U2S6 in organic solvents and or U2SO4 in polar protic solvent such as water and Cu 2+ sacrificial electrode.
• the glass, ceramic and or glass-ceramic sheet of solid-state electrolyte feature a pattern resembling the targeted distribution of the anisotropic lithiation (see Figure 2, 4, 5 and 6).
• a method of producing a negative electrode - silicon anode wherein the silicon fiber layers and/or the printer head is/are immersed into liquid processing medium(s).
• each print-fusing head/nozzle are electrically connected to monitor local spot-area resistivity of the Si anode body (wafer) and/or to monitor pressure build-up during expansion occurring by pre-lithiation where those parameters is used in such way that well balanced spot- fused points is made.
• This allows safer and faster lithiation of Si along the printer/dosing heads/nozzles trajectory or spot printing/fusing.
• Li spot printing/fusing interconnects the individual Si fiber layers while as droplets of molten lithium preferably going up through the layers of silicon during the spot-fusing process.
• a method of ex-situ pre-lithiation (preferably in the first stage) negative electrode - heterofibrous silicon anode wherein the flow of molten lithium towards the solvent immersed silicon layers is against gravity - defined as floating inside a suitable processing liquid, such as hydrocarbons as outlined above which is compatible with molten lithium and where the density of such liquid is > 0.65 g/cm3, thus higher than the density of the molten lithium.
• a suitable processing liquid such as hydrocarbons as outlined above which is compatible with molten lithium and where the density of such liquid is > 0.65 g/cm3, thus higher than the density of the molten lithium.
• a negative electrode for the use in alkali-ion rechargeable battery where electrochemically active material is selected from the Group IV semiconductors, the active material forming a heterofibrous monolithic anode body, the anode body comprises at least 3 layers of aligned and/or stacked and/or interlaced fibers.
• Figure 1 an example of a fuse spot distribution to interconnect separate layers of aligned and/or stacked and/or interlaced group IV, in particular silicon fibres,
• Figure 2 an exemplary set up for lithiation of the spot fused layered silicon anode body (wafer), patterned solid state (glass)-ceramic electrolyte (hexagonal) as-lithiation mask.
• the lithiation takes place in steps, e.g., as depicted in figure 2 in four steps, however it is not limited on this number of steps. Steps can be in between 1-100 steps lithiation is 1 st started preferably in the centre part 1 followed by the subsequent area to then 3 then 4 and so on.
• Figure 3 an abstract image of an over-lithiated silicon anode body
• Figure 4 Patterned solid state (glass)-ceramic electrolyte as-lithiation mask resembling the ex-situ lithiation in a process solvent/electrolyte.
• Figure 4 depicts the initial state with only limited lithiation and unexpanded silicon layers which are mechanically interlocked between each other by the fused spots.
• Figure 5 Patterned solid state (glass)-ceramic electrolyte as-lithiation mask resembling the ex-situ lithiation in a process solvent/electrolyte.
• Figure 5 depicts the intermediate state with partly lithiation and expanded silicon layers, which are anisotropically spot fused by lithium induced metallurgic bonds. The arrows mark the lithiation pathway,
• Figure 6 Patterned solid state (glass)-ceramic electrolyte as-lithiation mask resembling the ex-situ lithiation in a process solvent/electrolyte.
• Figure 6 depicts the complete state with (over)-lithiation and fully expanded silicon layers, which are anisotropically spot fused by lithium induced metallurgic bonds. The arrows mark the lithiation pathway.
• Figure 7 Lithiated (5-100%) silicon wafer monolithic body, including ex-situ fabricated artificial SEI layer,
• Figure 9 Lithiated (5-100%) silicon wafer anode monolith, including ex-situ fabricated artificial SEI layer attached on top of a graphene and/or reduced graphene oxide current foil including 3 tabs,
• Figure 10-13 show the relative volumetric extent of the layered silicon anode (late silicon wafer) in the different non-lithiated, partially lithiated and over lithiated states the size of the circles may only represent the increase in volume but not necessarily the actual percentage in volume or die me to increase,
• Figure 10 Silicon wafer anode in the state of the highest density
• Figure 11 Electrochemical lithiated silicon wafer anode in the state of room temperature active phase LhsS ,
• Figure 12 Electrochemical over-lithiated silicon wafer anode in the state of the high temperature active phase LhiSis featuring the maximum possible volume
• Figure 14 a top view on the relative orientation of 3 representative layers with aligned silicon fibres each alignment along the direction of the individual arrows of the same colour Layers of aligned and preferably 120° interlaced silicon fibers before pre-lithiation process,
• Figure 15 the setup of layers according to figure 14 after the pre-lithiation (spot fusing) process.

Landscapes

• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Composite Materials (AREA)
• Battery Electrode And Active Subsutance (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=83048515

Family Applications (1)

Country Status (7)

Family Cites Families (4)

• 2021
  • 2021-09-16 KR KR1020237012758A patent/KR20230069195A/ko unknown
  • 2021-09-16 US US18/026,267 patent/US20230361285A1/en active Pending
  • 2021-09-16 EP EP21785772.1A patent/EP4115459A1/en active Pending
  • 2021-09-16 JP JP2023516478A patent/JP2023541908A/ja active Pending
  • 2021-09-16 CA CA3195681A patent/CA3195681A1/en active Pending
  • 2021-09-16 WO PCT/EP2021/075551 patent/WO2022179719A1/en unknown
  • 2021-09-16 CN CN202180063116.8A patent/CN116438680A/zh active Pending

Also Published As

Similar Documents

Legal Events